Defects of vision
Intermediate
Myopia and hypermetropia corrected by lenses.
Myopia (short-sightedness): image forms in front of the retina; corrected by a diverging lens. Hypermetropia: behind the retina; corrected by a converging lens. Presbyopia: with age.
A myopic person with far point 2 m needs −0.5 D.
Astigmatism needs cylindrical lenses.
In more detail
Common vision defects include myopia (short-sightedness), hypermetropia (long-sightedness) and presbyopia. They are corrected with diverging or converging lenses, depending on the defect.
Real-world uses
- Opticians prescribe lenses to correct vision.
- Contact lenses and laser surgery correct many defects.
- Glasses and contact lenses correct myopia with diverging lenses, and hypermetropia with converging lenses.
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Frequently asked questions
What corrects myopia?
A diverging lens, which moves the focus back onto the retina.
What corrects hypermetropia?
A converging lens, which brings the focus forward.
What is myopia?
A condition in which distant objects are blurry because the eye focuses light in front of the retina.
Related topics in Optics
Combination of lenses · Lens aberrations · Human eye · Simple microscope · Compound microscope · Astronomical telescope